Turbine engines have been used to propel vehicles such as jets and to produce electrical power for industry and central power generation. Typically, a gas turbine consists of a compressor, a combustor, and a turbine in a sequential arrangement. Influent air is compressed to a high-pressure in the compressor and is fed at a high speed and pressure into the combustor, where the air is mixed with a fuel and is combusted to produce a hot, pressurized stream of gas that is passed into the turbine section where the gas expands and drives a turbine. The turbine converts the energy (e.g., enthalpy) of the gas into mechanical work used to drive the compressor and optionally other devices coupled to the gas turbine.
Recent technology advancements have enabled the production of small gas turbine engines that are lighter weight and cheaper than gasoline combustion engines used for most cars. Such turbine engines also produce less pollution. Diagrams of two conventional gas turbine engines are shown in FIGS. 1 and 2.
FIG. 1 shows a conventional gas turbine engine 10, which is typically used in power generation. The gas turbine 10 of FIG. 1 includes a compressor section 14 (which may have multiple stages) for increasing the pressure and temperature of influent air (e.g., at air intake 12); a combustion section or chamber 16 having multiple combustion chambers located around the perimeter of the engine, in which fuel is ignited to further increase the temperature and pressure of the influent air; and a turbine section 18 in which the hot, pressurized air or exhaust 20 is delivered to drive the rotors of the turbine and generate mechanical energy to spin the central axle of the turbine and generate power.
FIG. 2 shows a conventional turbofan turbine engine 50 that can be used for aircraft propulsion. The conventional turbofan engine 50 includes a large fan 52 at the front of the engine 50 that accelerates influent air and passes it into a low-pressure compressor 60 and/or high-pressure compressor 62 and into fan ducts 80 that pass along the outside of the engine 50. The compressors 60 and 62, a combustion chamber 70, and high-pressure and low-pressure turbine sections 72, 74 of the turbofan engine 50 work in a similar manner to the gas turbine engine 10 of FIG. 1. The operation of the turbofan engine 50 differs from the gas turbine engine 10, in that the “bypass flow” (the air that is accelerated by the fan 52 and passed through the fan duct 80) contributes to the total thrust produced by the engine.
Just about all conventional jet engines and most rocket engines operate on the deflagration of fuel, that is, the rapid but subsonic combustion of fuel. The combustion of fuel in the combustion chamber of conventional gas turbine and turbofan engines exerts force on the turbine blades and creates mechanical power. In such engines, the combustion chamber is an open system and the combustion of fuel is continual. The ignition sources in the combustion chamber (igniters) fire when the engine is started, but are then shut off because fuel and pressurized air from the compressor are constantly fed into the combustion chamber(s) while the engine is running, and ignition of the fuel is thereby sustained.
Although recent technology advancements have enabled the use of smaller, lighter gas turbines that are more efficient and less polluting than other engines types (e.g., combustion engines), the efficiency of gas turbines can be improved. For example, conventional natural gas-fired turbine generators convert only between 25 and 35 percent of the natural gas heating value to useable electricity. Therefore, the need exists for more efficient gas turbine technologies for propelling vehicles and producing electricity.
This “Discussion of the Background” section is provided for background information only. The statements in this “Discussion of the Background” are not an admission that the subject matter disclosed in this “Discussion of the Background” section constitutes prior art to the present disclosure, and no part of this “Discussion of the Background” section may be used as an admission that any part of this application, including this “Discussion of the Background” section, constitutes prior art to the present disclosure.